Bonsoir,

Développer:

A . ( x - 2 )( 3x +1 )= 3x²-6x+x-2= 3x²-5x-2

B. ( 6-3x ) ( 7x - 5)= 42x-21x²-30+15x= -21x²+57x-30

C. ( -x +3 ) ( x-3)= -x²+3x+3x-9= -x²+6x-9

D. ( -2-3x ) ( -4-5x)= 8+12x+10x+15x²= 15x²+22x+8

Bonsoir,

Développer et réduire les expressions:

A = (x - 2)(3x + 1)

A = x*3x + x*1 + (-2)*3x + (-2)*1

A = 3x² + x - 6x - 2

A = 3x² - 5x - 2

B = (6 - 3x)(7x - 5)

B = 6*7x + 6*(-5) + (-3x)*7x + (-3x)*(-5)

B = 42x - 30 - 21x² + 15x

B = -21x² + 57x - 30

C = (-x + 3)(x - 3)

C = (-x)*x + (-x)*(-3) + 3*x + 3*(-3)

C = -x² + 3x + 3x - 9

C = -x² + 6x - 9

D = (-2 - 3x)(-4 - 5x)

D = -2*(-4) + (-2)*(-5x) + (-3x)*(-4) + (-3x)*(-5x)

D = 8 + 10x + 12x + 15x²

D = 15x² + 22x + 8

• Distributivité double:

(a + b)(c + d) = ac + ad + bc + bd

* = multiplication

Bonne soirée